KR101332015B1 - Color image forming apparatus - Google Patents

Abstract

A color image forming apparatus according to the present invention includes a plurality of photoconductors, a photoconductor for scanning an optical beam by beams on the photoconductors, and a plurality of photoconductors for attaching a developer to each photoconductor to form a visible image. And a transfer drum to which the visible images formed on each photosensitive member are transferred and superimposed, a transfer device to transfer the visible images superimposed on the transfer drum onto a print medium, and a motor to rotate the transfer drum, wherein the transfer drum is provided with an external gear. A plurality of photosensitive members are provided with a photosensitive member driving gear connected to an external gear, and when the transfer drum is rotated by a motor, each photosensitive member rotates in association with the rotation of the transfer drum. According to the present invention, since each photosensitive member rotates in association with the transfer drum when the transfer drum rotates, the structure of the power transmission system from the motor to each photosensitive member is very simple.

Color image forming apparatus, photosensitive member, transfer drum, motor, power transmission

Description

Color image forming apparatus

1 is a side cross-sectional view schematically showing a color image forming apparatus according to an embodiment of the present invention.

2 is a side cross-sectional view schematically showing an image forming unit of a color image forming apparatus according to an embodiment of the present invention.

3 is a cross-sectional view taken along the line I-I of the image forming unit shown in FIG.

4 is an exploded view of the image forming unit shown in FIG. 3.

Description of the Related Art [0002]

10 ... Image forming apparatus main body 20 ... Print media loading unit

30 ... Pickup device 40 ... Feeding device

51, 52, 53, 54 ... developing 60 ... optical scanning device

70 ... Transfer Unit 80 ... Fixing Unit

90 Discharge Unit 100 Imaging Unit

111,121,131,141 ... Photosensitive member 112,122,132,142 ... Photosensitive driving gear

114,124,134,144 ... Charge 115,125,135,145 ... Cleaner

151 Warrior Drum 152 External Gear

153 Internal gear 161 Frame

171 ... motor 173 ... motor gear

181,183 Kids Gear

The present invention relates to an image forming apparatus, and more particularly, to a color image forming apparatus including a plurality of photosensitive members on which visible images are formed, and forming a color visible image by superimposing visible images of different colors formed on each photosensitive member. .

2. Description of the Related Art Generally, an image forming apparatus is a device for developing a monochrome image or a color image on a print medium such as paper in accordance with an image signal, and includes a laser printer, an inkjet printer, a copying machine, a multifunctional apparatus and a facsimile. Image forming methods of various image forming apparatuses include an electrophotographic method of scanning a beam to a photosensitive member to form an electrostatic latent image, and attaching a developer thereon to a printing medium, and spraying liquid ink onto the surface of the printing medium according to an image signal. The inkjet method is representative.

Among these, the electrophotographic image forming apparatus charges the surface of the photosensitive member to a constant potential and then scans a beam thereon to form an electrostatic latent image due to a potential difference, and attaches a developer to the electrostatic latent image to produce a visible image. . Then, the visible image formed on the photosensitive member is transferred to a printing medium, and then heat and pressure are applied to the printing medium to fix the visible image made of a powder developer on the surface of the printing medium to obtain a printed output.

An electrophotographic image forming apparatus includes a mono image forming apparatus for printing a black and white image and a color image forming apparatus for printing a color image. Since a mono image forming apparatus uses only a black developer, only one black developer is required, but a color image forming apparatus typically requires four colors (magenta, cyan, yellow, and black) to produce a color image.

Currently known electrophotographic color image forming apparatuses include a so-called multi-path type color image forming apparatus having one photosensitive member, and a so-called single-pass type in which a plurality of photosensitive members are provided for each developing device. path type) There is a color image forming apparatus.

In the multi-pass type color image forming apparatus, only one developer is operated while one photoreceptor is rotated to form a single color visible image on the photoreceptor, and the visible image formed on the photoreceptor is transferred before another developer is operated. This monochromatic visible image formation is repeated for the remaining developer. Therefore, in the multi-pass type color image forming apparatus, the exposure, development, and transfer processes are repeated four times in order to obtain one color image, and the visible images of each color are sequentially superimposed on the intermediate transfer apparatus, and then transferred to the print medium at once. do.

In contrast, in the single-pass type color image forming apparatus, a visible image of each color is formed on the photoconductors corresponding to each developer, and the visible image formed on each photoconductor is directly transferred to an intermediate transfer apparatus or a print medium, thereby forming an image as compared with the multipath type image forming apparatus. There is a short time advantage.

An example of such a single pass type color image forming apparatus is disclosed in Japanese Patent Laid-Open No. JP 11-52651 (published on Feb. 26, 1999). The conventional single-pass type color image forming apparatus disclosed in the above publication is a method in which visible images of each color made by four developing machines are sequentially transferred to a print medium transported by a belt and superimposed on the print medium. Each developing unit includes a photoconductor on which a visible image is formed, and each of the photoconductors is provided with a drive gear for power transmission. Then, the drive gear of each photosensitive member is connected to one photosensitive member driving motor through a gear train consisting of a plurality of gears.

However, in the conventional color image forming apparatus, since each photosensitive member is connected to the photosensitive member driving motor through a plurality of gears, the structure of the power transmission system is very complicated and the installation space increases due to the arrangement of the plurality of gears.

In addition, the rotational imbalance of each photosensitive member may occur due to manufacturing or assembly errors of the gear, and a color registration error may be generated due to the phase difference of each visible image transferred to the printing medium.

The present invention is to solve the above problems, the power transmission system for driving a plurality of photosensitive member is made of a simple structure and the installation space is small, the device can be miniaturized and compact, reducing the risk of color registration error It is an object of the present invention to provide a color image forming apparatus.

A color image forming apparatus according to the present invention for achieving the above object comprises a plurality of photoconductors, a light scanning device for scanning the beam to each photoconductor to form an electrostatic latent image, and attaching a developer to each photoconductor to visual image A plurality of developing devices for forming a plurality of photoconductors, a transfer drum to which visible images formed on each photosensitive member are transferred and superimposed thereon, a transfer device to transfer the visible images superimposed on the transfer drum onto a print medium, and a motor to rotate the transfer drum. The transfer drum is provided with an external gear, and the plurality of photosensitive members are provided with a photosensitive member drive gear connected to the external gear. When the transfer drum is rotated by the motor, each of the photosensitive members rotates of the transfer drum. Rotate in conjunction with the.

Here, each of the photosensitive member and the transfer drum may be rotatably supported on one frame.

The plurality of developing devices may be detachably coupled to the frame so as to correspond to the photosensitive members.

In addition, the outer diameter of each photosensitive member and the pitch circle outer diameter of each photosensitive member driving gear may be the same, and the outer diameter of the transfer drum and the outer diameter of the pitch circle of the external gear may be the same.

In addition, an internal gear is provided in the transfer drum, a motor gear is provided in the motor, and the motor may be installed in the transfer drum such that the motor gear is connected to the internal gear.

In addition, an idle gear for power transmission may be installed between the internal gear and the motor gear.

Hereinafter, a color image forming apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, a color image forming apparatus according to an embodiment of the present invention includes a plurality of photosensitive members 111 and 121 in which visible images of different colors (eg, magenta, cyan, yellow, and black) are formed. 131, 141, and the so-called single-pass type color image forming apparatus in which the visible images formed on the photosensitive members 111, 121, 131, and 141 are overlapped to form color images.

The color image forming apparatus according to an embodiment of the present invention includes an image forming apparatus main body 10, a print medium stacking device 20 on which a print medium is loaded, and a print medium stacked on the print medium stacking device 20. An image comprising a pick-up device 30 for picking up a sheet, a feeding device 40 for transferring the picked-up print medium, and a plurality of photosensitive members 111, 121, 131, 141 and a transfer drum 151. A plurality of developing units 51, 52, 53, 54, and a plurality of photoconductors 111 that attach a developer to the forming unit 100, the photoconductors 111, 121, 131, and 141, respectively. 121, 131, and 141, an optical scanning device 60 for scanning a beam, a transfer device 70 for transferring a color image formed on the transfer drum 151 to a print medium, and a printing in which the color image is transferred. And a fixing unit 80 for applying heat and pressure to the medium to fix the color image onto the printing medium, and a discharge device 90 for discharging the printing medium passing through the fixing unit 80.

Here, the printing medium stacking device 20, the pickup device 30, the feeding device 40, the optical scanning device 60, the transfer device 70, the fixing unit 80 and the discharge device 90 is conventional As such, the following description is made schematically.

In the color image forming apparatus according to the present invention, when printing is started, the pickup device 30 operates to pick up the print media loaded in the print media stacker 20 in a single sheet. The pick-up device 30 is rotatably positioned, but the pick-up device 30 is mounted on the loading plate because the enemy trial 21 provided in the print medium stacking device 20 lifts the print medium toward the pick-up device 30. A plurality of print media loaded on 21 can be picked up continuously. When the pickup device 30 picks up the print medium and transfers it to the feeding device 40, the feeding device 40 aligns the leading end of the print medium and transfers it to the image forming unit 100.

While the print media is transferred to the image forming unit 100, the chargers 114, 124, 134, 144 adjacent to each photoreceptor 111, 121, 131, 141 are each photoreceptor 111. (121) 131 (141) the surface of the charge to a predetermined potential, the optical scanning device 60 scans the beam to each photosensitive member (111) (121) (131) (141) in accordance with the image signal Electrostatic latent images are formed on the surfaces of the photoconductors 111, 121, 131, and 141. The optical scanning device 60 includes a light source (not shown) for generating a beam, a polygon mirror 61 for deflecting the beam within a predetermined angle range, and a photoconductor 111, 121, 131 as usual. (F) a lens 62 for scanning at a constant velocity toward the (141).

When the electrostatic latent image is formed on each of the photosensitive members 111, 121, 131, and 141, each developer 51, 52, 53 stores a developer having a different color (for example, magenta, cyan, yellow, and black). (54) attaches a developer to each of the photoconductors 111, 121, 131, and 141 to form visible images of different colors on the photoconductors 111, 121, 131, and 141. Then, the visible images of each color are sequentially transferred to the rotating transfer drum 151, and the transfer drum 151 forms a color image in which the visible images of each color overlap. Each of the developing devices 51, 52, 53, 54 and the developing rollers 51a, 52a, 53a, 54a attaching a developer to each photosensitive member 111, 121, 131, 141, And supply rollers 51b, 52b, 53b, 54b for supplying a developer to each of the developing rollers 51a, 52a, 53a, 54a.

The color image formed on the transfer drum 151 is transferred to the surface of the print medium when the print medium passes between the transfer drum 151 and the transfer device 70. When the print medium on which the color image is transferred is transferred to the fixing unit 80, the fixing unit 80 applies heat and pressure to the print medium to fuse the color image made of the powder developer onto the surface of the print medium. The fixing unit 80 includes a heating roller 81 having a heating element (not shown) as usual, and a pressure roller 82 in close contact with the heating roller 81.

Finally, the print medium passing through the fixing unit 80 is discharged to the outside of the image forming apparatus main body 10 by the discharge device 90.

The image forming unit 100, which is a main component of the present invention, includes a plurality of photosensitive members 111, 121, 131, 141, a transfer drum 151, and photosensitive members 111, 121, 131, 141. ) And a frame 161 rotatably supporting the transfer drum 151, and a motor 171 for driving the transfer drum 151 and the photosensitive members 111, 121, 131, and 141.

As shown in FIG. 2, the photosensitive members 111, 121, 131, and 141 and the transfer drum 151 are rotatably supported by the frame 161. In the frame 161, an opening 161a opened to allow the transfer device 70 (see FIG. 1) to be in contact with the transfer drum 151, and for the coupling of each of the developing devices 51, 52, 53, and 54. Coupling grooves 161b, 161c, 161d and 161e are provided. In the present invention, the plurality of developing devices 51, 52, 53, 54 may be integrally coupled to the frame 161.

The plurality of photosensitive members 111, 121, 131, and 141 have the same outer diameter (do; see FIG. 4), and are respectively installed to be in contact with the circumference of the transfer drum 151, and neighboring ones are spaced apart from each other. do. Chargers 114, 124, and 134 for charging the photosensitive members 111, 121, 131, and 141 to a predetermined electric potential around the respective photosensitive members 111, 121, 131, and 141 ( 144 and cleaners 115, 125, 135, and 145 for removing the developer remaining on the photoconductors 111, 121, 131, and 141 without being transferred to the transfer drum 151. Is installed.

The transfer drum 151 is made of a semiconductive rubber bonded to a hollow conductive drum. Semiconductive rubbers used in the transfer drum 151 include neoplan (CR), double synthetic rubber (EPDM), NBR (NBR), natural rubber (NB), silicone rubber, and the like. And, the surface of the transfer drum 151 is coated with a thickness of 0.01 ~ 0.02mm with urethane or fluorine rubber (FR) to improve the releasability of the developer. The resistance of the transfer drum 151 is usually 10E7Ωcm ~ 10E9Ωcm.

As illustrated in FIGS. 2 and 3, an external gear 152 is provided on an outer side of the transfer drum 151, and an internal gear 153 is provided on an inner side of the transfer drum 151. On one side of each of the photosensitive members 111, 121, 131, 141, photosensitive body driving gears 112, 122, 132, 142 connected to the external gear 152 of the transfer drum 151 are connected. Each is provided.

One end of each photoreceptor 111, 121, 131, 141 extends the photoreceptor shaft 113, and the photoreceptor drive gears 112, 122, 132, and 142 are connected to the photoreceptor shaft 113. Combined. The photosensitive member shaft 113 is rotatably coupled to the photosensitive member shaft support bearing 162 provided in the frame 161 to rotatably support each photosensitive member 111, 121, 131, 141. Although not shown, the other end of each photosensitive member 111, 121, 131, 141 is provided with a photosensitive member shaft extending outward, which is also rotatably coupled to a bearing provided in the frame 161. Then, both ends of the transfer drum 151 are rotatably coupled to the drum support bearing 163 provided in the frame 161. Therefore, when the transfer drum 151 rotates, each of the photosensitive member driving gears 112, 122, 132, 142 and each of the photosensitive members 111, 121, 131, and 141 rotate in synchronization with this.

The motor 171 is coupled to the frame 161 to be located inside the transfer drum 151. The frame 161 is provided with a plurality of coupling pillars 164, and the motor 171 is fixed to the coupling pillar 164 through a fastening member B such as a screw. The motor gear 173 is coupled to the motor shaft 172 provided in the motor 171, and the motor shaft 172 is rotatably coupled to the motor shaft support bearing 165 provided in the frame 161. The motor gear 173 is connected to the internal gear 153 of the transfer drum 151 through a pair of idle gears 181 and 183 rotatably supported by the frame 161. Each idle gear 181, 183 includes a gear shaft 182, and the gear shaft 182 is rotatably coupled to the gear shaft support bearing 166 provided in the frame 161. Accordingly, when the motor gear 173 is rotated by the driving of the motor 171, the pair of idle gears 181 and 183 rotate, thereby causing the transfer drum 151 to rotate.

As shown in FIG. 4, the outer diameter (do) of each photosensitive member 111, 121, 131, and 141 and the respective photosensitive member driving gears 112, 122, 132 in contact with the external gear 152 ( The outer diameter dg of the pitch circle 112a of 142 is the same, and the outer diameter Dd of the transfer drum 151 and the outer diameter Dg of the pitch circle 152a of the external gear 152 are the same. As a result, the flux on the surfaces of the photosensitive members 111, 121, 131, and 141 and the flux on the surface of the transfer drum 151 become equal.

As shown in FIG. 2, when the motor gear 173 rotates in the counterclockwise direction, the pair of idle gears 181 and 183 geared to the motor gear 173 are clocked. Rotate in the direction. Along with the idle gears 181 and 183, the internal gear 153 of the transfer drum 151 and the external gear 152 integrally therewith rotate in a clockwise direction and are connected to the external gear 152. Each photosensitive member drive gear 112, 122, 132, 142 rotates counterclockwise.

As described above, in the color image forming apparatus according to the present invention, the driving force of the motor 171 installed in the transfer drum 151 is transferred to the transfer drum through the motor gear 173 and the pair of idle gears 181 and 183. It is transmitted to the internal gear 153 integrally provided in the 151, the rotational force of the transfer drum 151 through the external gear 152 integrally provided in the transfer drum 151, each photosensitive member 111, 121 ( Since it is transmitted to the photosensitive member drive gears 112, 122, 132, 142 integrally coupled to the 131, 141, from the motor 171 to the transfer drum 151, and also each photosensitive member in the motor 171 The structure of the power train up to (111) 121, 131, 141 is simple, and the power transmission route is short.

According to the present invention described above, since the photosensitive member driving gear provided to each photosensitive member is geared to the outer ring gear provided integrally to the transfer drum and receives the driving force from the outer ring gear, each photosensitive member is interlocked with it when the transfer drum rotates. To rotate. Therefore, the structure of the power transmission system from the motor to each photoconductor is very simple and the installation space is small compared to the prior art, so that the device can be miniaturized and compact.

In addition, according to the present invention, since the number of gears for power transmission to each photosensitive member can be significantly reduced, the rotational imbalance of each photosensitive member due to the manufacturing error of the gears or the assembly error between the gears can be greatly reduced. Color registration errors can be reduced.

The present invention described above is not limited to the configuration and operation as illustrated and described. That is, the present invention is capable of various changes and modifications within the spirit and scope of the appended claims.

Claims (6)

A plurality of photoconductors, an optical scanning device for scanning the beams to form electrostatic latent images, a plurality of photoconductors for attaching a developer to each photoconductor to form a visible image, and a visible image formed on each photoconductor What is claimed is: 1. A color image forming apparatus comprising: a transfer drum for superimposing and overlapping a transfer drum; And a motor for rotating the transfer drum, wherein the transfer drum is provided with an external gear, and the plurality of photosensitive members are provided with a photosensitive member drive gear connected to the external gear, and the transfer drum is rotated by the motor. And the respective photosensitive members rotate in association with the rotation of the transfer drum. The method of claim 1, Each of the photosensitive member and the transfer drum is rotatably supported in one frame. The method of claim 2, And the plurality of developing devices are detachably coupled to the frame so as to correspond to the respective photosensitive members. The method of claim 1, And an outer diameter of each of the photosensitive members and an outer diameter of the pitch circle of each of the photosensitive member driving gears, and an outer diameter of the transfer drum and an outer diameter of the pitch circle of the external gears. The method of claim 1, An internal gear is provided in the transfer drum, a motor gear is provided in the motor, and the motor is installed in the transfer drum such that the motor gear is connected to the internal gear. Device. 6. The method of claim 5, And an idler gear for power transmission between the internal gear and the motor gear.

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